1. Field of the Invention
This invention relates to the field of digital correlation and more particularly to counter circuitry used in a digital correlator.
2. Description of the Prior Art
Included in the prior art is a digital correlation method and apparatus which makes use of an exclusive-OR multiplier, a digital counter, and a microprocessor. Typically, a signal is multiplied by a reference in the exclusive-OR to produce a logic one at the output when the inputs are the same, and a logic zero at the output when the inputs are not the same. The bit stream out of the exclusive-OR is assembled into binary words by the counter. The counter operates for a fixed period, and the binary words are output to the microprocessor at a constant rate. This digital correlation method, which is used in random signal radar for the recovery of the received signal from receiver noise, was devised to save much of the space and cost associated with analog circuits. However, a high resolution random signal radar often requires implementation of many correlators, resulting in the devotion of much space to the correlator hardware. The major user of space in the digital correlator is the counter. Thus, there is a need in the art for a method of performing the counter function while utilizing less space.